The present invention relates generally to cooling towers and more particularly but not by way of limitation to a cooling tower with a collection system that includes a pre-collector for directing water into a plurality of collection troughs.
A counterflow cooling tower, which is one common type of industrial cooling tower known in the art, is one wherein water falls downward through a fill material while cooling air moves upward through the fill material. The term "counterflow" refers to the fact that the water and air are moving in opposite directions. Counterflow cooling towers traditionally may be of three types, namely, induced draft, natural draft, and forced draft.
An induced draft counterflow cooling tower has a fan located on top of the tower which sucks air up through the fill material. Examples of such towers are seen in U.S. Pat. Nos. 4,267,130 and 4,301,097, both to Curtis.
Natural draft cooling towers do not utilize fans to assist air flow but rely on the natural tendency of warm air to flow upward. A natural draft counterflow cooling tower is shown at FIG. 1 of U.S. Pat. No. 4,521,350 to LeFevre. The LeFevre patent shows the use of a drainage collection system below the fill material in the natural draft counterflow cooling tower shown therein.
Forced draft counterflow cooling towers, examples of which are shown in U.S. Pat. Nos. 2,606,750 and 2,915,302 to Jacir, traditionally have a fan located on the side of the tower which blows air into a plenum chamber on a lower side of the tower. Vanes are used to turn the air 90.degree. to direct it upward through the tower. The term "forced draft" is understood to refer to a system like that of Jacir having a fan on the side of the tower blowing into a lower plenum so the air must then turn 90.degree. to flow upward through the tower.
Other forced draft cooling towers, referred to herein as direct forced draft counterflow cooling towers, have a fan located below the fill material for forcing air directly upward therethrough. Examples of direct forced draft counterflow cooling towers are shown in U.S. Pat. No. 5,227,095 to Curtis issued Jul. 13, 1993, U.S. Pat. No. 5,487,531 to Curtis, issued Jan. 30, 1996, and U.S. Pat. No. 5,545,356 to Curtis, issued Aug. 13, 1996, the details of all three of which are incorporated herein by reference.
The prior art includes many versions of drainage collection systems used in cooling towers for collecting the liquid falling through the tower. Several of the prior art collection systems are made up of a series of overlapping sloped collection plates with troughs along their lower edge. One such system is shown, for example, in the LeFevre U.S. Pat. No. 4,521,350 patent cited above. Other such systems are shown in U.S. Pat. No. 5,227,095 to Curtis. A dual layered drainage collection system, which includes an upper layer of parallel elongated collection plates and a lower layer of parallel elongated collection plates, is shown in U.S. Pat. No. 5,487,531. Although the collection systems shown in the aforementioned patents perform adequately, there is a continuing need for collection systems that will collect substantially all of the water falling in a cooling tower, especially in direct forced draft counterflow cooling towers to prevent the water from reaching the fan, to eliminate or at least lessen icing problems in cold weather climates, and at the same time to decrease the pressure drop which is created when the air flowing upward through the cooling tower is interrupted by and forced to flow around the various components in the interior of the cooling tower, such as the collection system.